U.S. patent number 10,821,571 [Application Number 15/778,902] was granted by the patent office on 2020-11-03 for handheld, hand-guided cutting-off machine.
This patent grant is currently assigned to Hilti Aktiengesellschaft. The grantee listed for this patent is Hilti Aktiengesellschaft. Invention is credited to Ralf Greitmann, Helmut Specht, Guenther Veik.
![](/patent/grant/10821571/US10821571-20201103-D00000.png)
![](/patent/grant/10821571/US10821571-20201103-D00001.png)
![](/patent/grant/10821571/US10821571-20201103-D00002.png)
![](/patent/grant/10821571/US10821571-20201103-D00003.png)
![](/patent/grant/10821571/US10821571-20201103-D00004.png)
![](/patent/grant/10821571/US10821571-20201103-D00005.png)
United States Patent |
10,821,571 |
Greitmann , et al. |
November 3, 2020 |
Handheld, hand-guided cutting-off machine
Abstract
A handheld, hand-guided cutting-off machine (10), which includes
a rotating cutting-off wheel, a supporting housing part (36), an
output shaft, which is rotatably supported around an output axis
(40), a drive motor, a transmission mechanism (19), which connects
the drive motor to the output shaft, a flange and a safety guard
(24), which covers the cutting-off wheel over a covering area. The
cutting-off wheel is rotatably fixedly mounted on the output shaft
with the aid of the flange and surrounded by the safety guard (24),
which is pivotable around a pivot axis. The safety guard (24), the
supporting housing part (36) and the transmission mechanism (19)
have maximum distances from the output axis (40) over an outcut
angle (.theta.), which are less than or equal to half the flange
diameter of the flange.
Inventors: |
Greitmann; Ralf (Kaufering,
DE), Veik; Guenther (Maeder, AT), Specht;
Helmut (Bad Woerishofen, DE) |
Applicant: |
Name |
City |
State |
Country |
Type |
Hilti Aktiengesellschaft |
Schaan |
N/A |
LI |
|
|
Assignee: |
Hilti Aktiengesellschaft
(Schaan, LI)
|
Family
ID: |
1000005155070 |
Appl.
No.: |
15/778,902 |
Filed: |
November 15, 2016 |
PCT
Filed: |
November 15, 2016 |
PCT No.: |
PCT/EP2016/077667 |
371(c)(1),(2),(4) Date: |
May 24, 2018 |
PCT
Pub. No.: |
WO2017/089169 |
PCT
Pub. Date: |
June 01, 2017 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20180345444 A1 |
Dec 6, 2018 |
|
Foreign Application Priority Data
|
|
|
|
|
Nov 25, 2015 [EP] |
|
|
15196162 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B23Q
11/06 (20130101); B24B 27/08 (20130101); B24B
23/02 (20130101); B24B 55/052 (20130101) |
Current International
Class: |
B24B
27/08 (20060101); B24B 55/05 (20060101); B24B
23/02 (20060101); B23Q 11/06 (20060101) |
Field of
Search: |
;451/358 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
102004035876 |
|
Dec 2005 |
|
DE |
|
102005049766 |
|
Feb 2010 |
|
DE |
|
1053829 |
|
Nov 2000 |
|
EP |
|
1609572 |
|
Dec 2005 |
|
EP |
|
2431603 |
|
May 2007 |
|
GB |
|
2006110969 |
|
Apr 2006 |
|
JP |
|
5526442 |
|
Jun 2014 |
|
JP |
|
Primary Examiner: Nguyen; George B
Attorney, Agent or Firm: Davidson, Davidson & Kappel,
LLC
Claims
What is claimed is:
1. A handheld, hand-guided cutting-off machine comprising: a
supporting housing part; a cutting-off wheel having a wheel
diameter; an output shaft rotatably supported around an output axis
on the housing part with the aid of a bearing element; a drive
motor and a transmission mechanism connecting the drive motor to
the output shaft, the transmission mechanism being situated on the
housing part; a flange having a flange diameter, the cutting-off
wheel being rotatably fixedly situatable on the output shaft with
the aid of the flange; and a safety guard having a covering area at
least partially covering the cutting-off wheel, and a machining
area exposing the cutting-off wheel, the safety guard being
pivotably supported around a pivot axis on the housing part; the
flange diameter of the flange corresponding to a minimum flange
diameter, and the safety guard having a first maximum distance from
the output axis over a first angle range, the supporting housing
part having a second maximum distance from the output axis over a
second angle range, and the transmission mechanism has a third
maximum distance from the output axis over a third angle range,
wherein the first, second and third maximum distances are less than
or equal to half the minimum flange diameter.
2. The cutting-off machine as recited in claim 1 wherein the safety
guard is adjustable between a front and a rear pivot position, an
outcut angle formed as an intersection between the first, second
and third angle ranges, being different than zero for at least one
pivot position of the safety guard.
3. The cutting-off machine as recited in claim 2 wherein the outcut
angle is different than zero for all pivot positions of the safety
guard between the front and the rear pivot positions.
4. The cutting-off machine as recited in claim 1 wherein the pivot
axis of the safety guard is displaced with respect to the output
axis of the output shaft by a distance into the covering area of
the safety guard.
5. The cutting-off machine as recited in claim 4 wherein a size of
the first angle range is dependent on a pivot position of the
safety guard.
6. The cutting-off machine as recited in claim 1 wherein the
transmission mechanism includes an output disk situated on the
output shaft, and a transmission element transmitting a movement of
the drive motor to the output disk, the output disk having a fourth
maximum distance and the transmission element having a fifth
maximum distance from the output axis over the third angle range,
wherein the fourth and fifth maximum distances are less than or
equal to half the minimum flange diameter.
7. The cutting-off machine as recited in claim 6 wherein the
transmission mechanism includes a cover covering the output disk
and the transmission element, the cover having a sixth maximum
distance from the output axis over the third angle range, the sixth
maximum distance being less than or equal to half the minimum
flange diameter.
8. The cutting-off machine as recited in claim 7 wherein the drive
motor is a combustion motor, and the cutting-off wheel is designed
as a diamond cutting-off wheel or as an abrasive cutting-off
wheel.
9. The cutting-off machine as recited in claim 1 wherein the drive
motor is an electric motor, and the cutting-off wheel is designed
as a diamond cutting-off wheel or as a bound, reinforced
cutting-off wheel.
Description
The present invention relates to a handheld, hand-guided
cutting-off machine.
BACKGROUND
Cutting-off machines are handheld, hand-guided power tools, which
include a machining tool designed in the form of a rotating
cutting-off wheel. The key components of a cutting-off machine
include, in addition to the cutting-off wheel, a supporting housing
part, an output shaft, which is rotatably supported around an
output axis, a drive motor, a transmission mechanism, which
connects the drive motor to the output shaft, a flange and a safety
guard, which covers the cutting-off wheel over a covering area. The
cutting-off wheel is rotatably fixedly mounted on the output shaft
with the aid of the flange and surrounded by the safety guard,
which is pivotably supported around a pivot axis. The pivot axis of
the safety guard is situated coaxially to the output axis, which
corresponds to the rotation axis of the cutting-off wheel. DE 10
2005 049 766 B4 discloses a handheld, hand-guided cutting-off
machine of this type.
The European standard EN ISO 19432:2012 and the U.S. standard ANSI
B175.4-2013 define safety requirements and measures for testing the
structural design of handheld, hand-guided cutting-off machines,
which include a built-in combustion motor for one-man operation and
are designated for cutting building materials, for example asphalt,
concrete, stone and metal, and which apply to cutting-off machines
which are provided for use with a rotating cutting-off wheel having
cutting-off bodies made of bound abrasive material and/or grinding
tools having diamond or CBN abrasive materials, which are mounted
centrally on a spindle shaft and are driven thereby, the front face
of the cutting-off wheel rotating in a direction facing away from
the user. The standards define a minimum flange diameter for the
flange, depending on the type and wheel diameter of a cutting-off
wheel. With regard to the type of cutting-off wheels, a distinction
is made between diamond cutting-off wheels and abrasive cutting-off
wheels, and with regard to wheel diameter D of the cutting-off
wheels, a distinction is made between four ranges (D.ltoreq.250 mm,
250 mm<D.ltoreq.300 mm, 300 mm<D.ltoreq.350 mm and 350
mm<D). The European standard EN ISO 19432:2012 applies to
cutting-off wheels having a maximum wheel diameter of 400 mm, and
the US standard ANSI B175.4-2013 applies to cutting-off wheels
having a maximum wheel diameter of 406 mm.
The European standard EN IEC 60745-2-22:2011 and the U.S. standard
ANSI/UL 60745-2-22-2012 apply to hand-guided, motor-operated
electric power tools in the form of cutting-off machines, which are
provided with a rotating cutting-off wheel having wheel diameters
from 55 mm to 410 mm for cutting off materials such as metal,
concrete, masonry, glass and tile. The standards define a minimum
flange diameter for the flange, depending on the type, wheel
diameter D and bore diameter O of a cutting-off wheel. Regarding
the type of cutting-off wheels, a distinction is made between
diamond cutting-off wheels and bound, reinforced cutting-off wheels
of type 41 or 42. Minimum flange diameter d.sub.min is
d.sub.min=0.15*D for diamond cutting-off wheels having a wheel
diameter D of 55 mm.ltoreq.D.ltoreq.410 mm. For bound, reinforced
cutting-off wheels of type 41 or 42, a distinction is made between
four ranges for wheel diameter D (55 mm.ltoreq.D<80 mm, 80
mm.ltoreq.D<105 mm, 105 mm.ltoreq.D 230 mm and 230
mm<D.ltoreq.410 mm), and a distinction is made between bore
diameters O of 10 mm and 16 mm for wheel diameter D where 80
mm.ltoreq.D<105 mm.
The maximum cutting depth achievable by a cutting-off wheel in a
workpiece is defined by half the difference between the wheel
diameter of the cutting-off wheel and the assigned minimum flange
diameter of the flange. In practice, diamond cutting-off wheels
having wheel diameters of 300 mm and 350 mm are primarily used in
cutting-off machines which include a combustion motor. The maximum
cutting depth achievable by a diamond cutting-off wheel having a
wheel diameter of 300 mm is 127.5 mm, and the maximum cutting depth
achievable by a diamond cutting-off wheel having a wheel diameter
of 350 mm is 148.75 mm.
The actual cutting depths achievable by known cutting-off machines
in a workpiece are less than the specified maximum cutting depths
defined by half the difference between the wheel diameter and the
minimum flange diameter. The equipment manufacturer Stihl offers
different gas-powered cutting-off machines, the cutting-off
machines TS 400, TS 410 and TS 420, among others. The TS 400
cutting-off machines are provided for diamond cutting-off wheels
and may be operated with different wheel diameters of 300 mm and
350 mm. According to the manufacturer's information, the cutting
depth achievable by the TS 400 cutting-off machine with a wheel
diameter of 300 mm is 100 mm, and according to the manufacturer's
information, the maximum cutting depth achievable by the TS 400
cutting-off machine with a wheel diameter of 350 mm is 125 mm. The
TS 410 cutting-off machines are provided for diamond cutting-off
wheels having a wheel diameter of 300 mm, and the TS 420
cutting-off machines are provided for diamond cutting-off wheels
having a wheel diameter of 350 mm. According to the manufacturer's
information, the maximum cutting depth achievable by the TS 410
cutting-off machine is 100 mm, and according to the manufacturer's
information, the maximum cutting depth achievable by the TS 420
cutting-off machine is 125 mm.
The cutting depths achievable by the TS 400 cutting-off machine
with a wheel diameter of 300 mm and the TS 410 cutting-off machine
are 20% less than the maximum cutting depth of 127.5 mm, and the
cutting depths achievable by the TS 400 cutting-off machine with a
wheel diameter of 350 mm and the TS 420 cutting-off machine are
approximately 16% less than the maximum cutting depth of 148.75 mm.
The flanges which Stihl uses in the TS 400, TS 410 and TS 420
cutting-off machines have a flange diameter of at least 103 mm. In
the TS 400 cutting-off machines, which may be operated with
different wheel diameters of 300 mm and 350 mm, the same flange
diameter of at least 103 mm is provided for the different wheel
diameters. The flange diameters used are much larger than minimum
flange diameter d.sub.min, which the European standard EN ISO
19432:2012 and the U.S. standard ANSI B175.4-2013 require for
diamond cutting-off wheels having a wheel diameter of 300 mm
(d.sub.min.gtoreq.45 mm) and a wheel diameter of 350 mm
(d.sub.min.gtoreq.52.5 mm). The standards apply to cutting-off
machines which were manufactured on or after the publication date
of the standards and not to cutting-off machines which were
manufactured before the publication date of the standards. The
previous versions of the standards have also defined the same
minimum flange diameters of 45 mm and 52.5 mm for diamond
cutting-off wheels having wheel diameters of 300 mm and 350 mm.
SUMMARY OF THE INVENTION
It is an object of the present invention to further develop a
handheld, hand-guided cutting-off machine in such a way that the
cutting depth achievable with a cutting-off wheel in a workpiece is
increased compared to the known cutting-off machines, and
preferably the maximum cutting depth is achieved, which is defined
by half the difference between the wheel diameter of the
cutting-off wheel and the minimum flange diameter of the
flange.
According to the present invention, the handheld, hand-guided
cutting-off machine is characterized in that the flange diameter of
the flange corresponds to a minimum flange diameter, and the safety
guard has maximum distances from the output axis over a first angle
range, the supporting housing part has maximum distances from the
output axis over a second angle range, and the transmission
mechanism has maximum distances from the output axis over a third
angle range, which are less than or equal to half the minimum
flange diameter. The flange diameters which are specified as the
lower limiting values for the flange in the particular, applicable
standards are defined as minimum flange diameters. Among other
things, the minimum flange diameter is dependent on the type of
drive motor, the type of cutting-off wheel and the wheel diameter
of the cutting-off wheel.
In the cutting-off machine according to the present invention, the
safety guard has a first outer contour having a first maximum
distance from the output axis, and the angle range, in which the
first outer contour of the safety guard has distances from the
output axis which are less than or equal to half the minimum flange
diameter, is defined as the first angle range. The supporting
housing part has a second outer contour having a second maximum
distance, and the angle range, in which the second outer contour of
the supporting housing part has distances from the output axis
which are less than or equal to half the minimum flange diameter,
is defined as the second angle range. The transmission mechanism
has a third outer contour having a third maximum distance from the
output axis, and the angle range, in which the third outer contour
of the transmission mechanism has distances from the output axis
which are less than or equal to half the minimum flange diameter,
is defined as the third angle range. The design of the first,
second and third outer contours makes it possible to achieve the
maximum cutting depth defined as half the difference between the
wheel diameter of the cutting-off wheel and the minimum flange
diameter with the aid of the cutting-off machine according to the
present invention. Among other things, the maximum cutting depth is
dependent on the type of drive motor, the type of cutting-off wheel
and the wheel diameter of the cutting-off wheel. The maximum
cutting depth is achieved at an operating angle of the cutting-off
machine, in which the first, second and third outer contours have
maximum distances from the output axis, which are less than or
equal to half the minimum flange diameter. The maximum cutting
depth is achievable only if the intersection between the first,
second and third angle ranges is different than zero.
In one specific embodiment, the safety guard is adjustable between
a front and a rear pivot position, an outcut angle, which is formed
as the intersection between the first, second and third angle
ranges, is different than zero for at least one pivot position of
the safety guard. The safety guard is pivotable around the pivot
axis and adjustable between a front pivot position and a rear pivot
position, it being possible to situate the safety guard in discrete
pivot positions or in any arbitrary pivot position between the
front and rear pivot positions. The first outer contour of the
safety guard is designed to be adjustable around the pivot axis;
the second outer contour of the supporting housing part and the
third outer contour of the transmission mechanism are designed to
be not adjustable. When the safety guard is moved around the pivot
axis, the position of the first angle range changes relative to the
second and third angle ranges. In the outcut angle, the three
components of the cutting-off machine according to the present
invention which are designed as the safety guard, supporting
housing part and transmission mechanism have distances from the
output axis which are less than or equal to half the minimum flange
diameter. When the operating angle of the cutting-off machine
according to the present invention is within the outcut angle, the
maximum cutting depth is achievable, which is defined as half the
difference between the wheel diameter of the cutting-off wheel and
the minimum flange diameter.
The outcut angle is particularly preferably different than zero for
all pivot positions of the safety guard between the front and the
rear pivot positions. In the outcut angle, the three components
which are designed as the safety guard, supporting housing part and
transmission mechanism have distances from the output axis which
are less than or equal to half the minimum flange diameter. In the
cutting-off machine according to the present invention, if the
outcut angle is different than zero for all pivot positions of the
safety guard, the maximum cutting depth is achievable in each pivot
position of the safety guard. The cutting-off machine must be
oriented by the operator in such a way that the operating angle is
within the outcut angle.
The pivot axis of the safety guard is particularly preferably
displaced with respect to the output axis of the output shaft by a
distance 4 into the covering area of the safety guard. The safety
guard is includes the covering area, which covers the cutting-off
wheel, and the machining area, which exposes the cutting-off wheel
for machining a workpiece. To achieve a preferably great cutting
depth with the aid of a cutting-off wheel, a flange having a
preferably small flange diameter is used. In the cutting-off
machine according to the present invention, a flange having the
minimum flange diameter is used; the minimum flange diameter
corresponds to the smallest flange diameter possible according to
the standards. The smaller the flange diameter is selected, the
smaller is the receiving area for the arrangement and support of
the components (bearing for the output shaft, safety guard,
supporting housing part and transmission mechanism), the support of
the safety guard being particularly critical. The safety guard
includes a fastening flange, which is mounted on a matching
counter-contour of the supporting housing part and is adjustable
around the pivot axis with respect to the counter-contour. If the
pivot axis of the safety guard coincides with the output axis of
the output shaft, the diameter of the fastening flange is limited
by the minimum flange diameter. The diameter of the fastening
flange is a variable which is essentially defined by the size and
weight of the safety guard in pivotable safety guards which are
adjustable via frictional engagement. Due to the displacement of
the pivot axis into the covering area of the safety guard, the
diameter of the fastening flange may be selected to be larger than
the flange diameter of the flange used. The displacement of the
pivot axis with respect to the output axis is particularly
advantageous if the diameter of the fastening flange is to be
optimally adapted to the size and weight of the safety guard.
The size of the first angle range is particularly preferably
dependent on the pivot position of the safety guard. The safety
guard is adjustable around the pivot axis, and the position of the
first angle range changes during the pivoting relative to the
second angle range of the supporting housing part and the third
angle range of the transmission mechanism. If the pivot axis is
displaced with respect to the output axis, the size of the first
angle range may change during the pivoting.
In one preferred embodiment of the cutting-off machine according to
the present invention, the transmission mechanism includes an
output disk, which is situated on the output shaft, and a
transmission element, which transmits a movement of the drive motor
to the output disk, the output disk and the transmission element
having maximum distances from the output axis over the third angle
range, which are less than or equal to half the minimum flange
diameter. The transmission mechanism is one of the components of
the cutting-off machine which are situated in the receiving area.
The condition that the maximum distance of the transmission
mechanism from the output axis is less than or equal to half the
minimum flange diameter in the third angle range must be met for
all subcomponents of the transmission mechanism. These include the
output disk, which is situated on the output shaft, and the
transmission element, which is situated on the output disk. The
output disk has a fourth maximum distance from the output axis, and
the transmission element has a fifth maximum distance from the
output axis.
The transmission mechanism particularly preferably includes a
cover, which covers the output disk and the transmission element,
the cover having a maximum distance from the output axis over the
third angle range, which is less than or equal to half the minimum
flange diameter. The subcomponents of the transmission mechanism
which are designed as the output disk and the transmission element
are rotating components, which must be covered to meet safety
requirements. The cover has a sixth maximum distance from the
output axis.
In a first variant of the cutting-off machine according to the
present invention, the drive motor is designed as a combustion
motor, and the cutting-off wheel is designed as a diamond
cutting-off wheel or as an abrasive cutting-off wheel. The European
standard EN ISO 19432:2012 applies to gas-powered cutting-off
machines in Europe, and the U.S. standard ANSI B175.4-2013 applies
thereto in the United States. Comparable standards are valid in
other countries or regions outside Europe and the United States,
and the European standard may be implemented in national standards
in European countries. In cutting-off machines according to the
present invention which include a combustion motor and a diamond
cutting-off wheel, minimum flange diameter d.sub.min is:
d.sub.min=37.5 mm for D.ltoreq.250 mm, d.sub.min=45 mm for 250
mm<D.ltoreq.300 mm, d.sub.min=52.5 mm for 300 mm<D.ltoreq.350
mm and d.sub.min=60 mm for 350 mm<D. In cutting-off machines
which include a combustion motor and an abrasive cutting-off wheel,
minimum flange diameter d.sub.min is: d.sub.min=63.5 mm for
D.ltoreq.250 mm, d.sub.min=75 mm for 250 mm<D.ltoreq.300 mm,
d.sub.min=87.5 mm for 250 mm<D.ltoreq.350 mm and d.sub.min=100
mm for 350 mm<D.
A cutting-off machine according to the present invention which
includes a combustion motor and a diamond cutting-off wheel
achieves a maximum cutting depth of 106.25 mm (1/2*(250 mm-37.5
mm)) with a wheel diameter of 250 mm, a maximum cutting depth of
127.5 mm (1/2*(300 mm-45 mm)) with a wheel diameter of 300 mm, a
maximum cutting depth of 148.75 mm (1/2*(350 mm-52.5 mm)) with a
wheel diameter of 350 mm and a maximum cutting depth of 170 mm
(1/2*(400 mm-60 mm)) with a wheel diameter of 400 mm. A cutting-off
machine according to the present invention which includes a
combustion motor and an abrasive cutting-off wheel, achieves a
maximum cutting depth of 93.25 mm (1/2*(250 mm-63.5 mm)) with a
wheel diameter of 250 mm, a maximum cutting depth of 112.5 mm
(1/2*(300 mm-75 mm)) with a wheel diameter of 300 mm, a maximum
cutting depth of 131.25 mm (1/2*(350 mm-87.5 mm)) with a wheel
diameter of 350 mm and a maximum cutting depth of 150 mm (1/2*(400
mm-100 mm)) with a wheel diameter of 400 mm.
In a second variant of the cutting-off machine according to the
present invention, the drive motor is designed as an electric
motor, and the cutting-off wheel is designed as a diamond
cutting-off wheel or as a bound, reinforced cutting-off wheel of
type 41 or 42. The European standard EN IEC 60745-2-22:2011 applies
to cutting-off machines which include an electric motor in Europe,
and the U.S. standard ANSI/UL 60745-2-22-2012 applies thereto in
the United States. Comparable standards are valid in other
countries or regions outside Europe and the United States, and the
European standard may be implemented in national standards in
European countries. For cutting-off machines according to the
present invention which include an electric motor and a diamond
cutting-off wheel, minimum flange diameter d.sub.min is:
d.sub.min=0.15*D for 55 mm.ltoreq.D.ltoreq.410 mm. For cutting-off
machines according to the present invention which include an
electric motor and a bound, reinforced cutting-off wheel of type 41
or 42, minimum flange diameter d.sub.min is: d.sub.min=19 mm for 55
mm.ltoreq.D<80 mm, d.sub.min=19 mm where O=10 mm and
d.sub.min=28 mm where O=16 mm for 80 mm.ltoreq.D<105 mm,
d.sub.min=40 mm for 105 mm.ltoreq.D.ltoreq.230 mm and
d.sub.min=0.25*D for 230 mm<D.ltoreq.410 mm.
BRIEF DESCRIPTION OF THE DRAWINGS
Exemplary embodiments of the present invention are described below
on the basis of the drawing. The latter is not necessarily intended
to represent the exemplary embodiments true to scale but rather the
drawing is presented in a schematic and/or slightly distorted form
where useful for the purpose of explanation. It should be taken
into account that a variety of modifications and changes relating
to the form and detail of a specific embodiment may be undertaken
without deviating from the general idea of the present invention.
The general idea of the present invention is not limited to the
exact form or the detail of the preferred specific embodiment
illustrated and described below, nor is it limited to an object
which would be limited in comparison to the object claimed in the
claims. In given measurement ranges, values within the specified
limits are also to be disclosed as limiting values and be able to
be arbitrarily used and claimed. For the sake of simplicity, the
same reference numerals are used below for identical or similar
parts or for parts having identical or similar functions.
FIGS. 1A, 1B show a handheld, hand-guided cutting-off machine
according to the present invention, including a cutting-off
wheel;
FIGS. 2A, 2B show a safety guard and a belt drive of the
cutting-off machine illustrated in FIGS. 1A, 1B, including a cover
(FIG. 2A) and without a cover (FIG. 2B);
FIGS. 3A, 3B show the safety guard of the cutting-off machine in a
front pivot position (FIG. 3A) and a rear pivot position (FIG.
3B);
FIGS. 4A, 4B show the supporting housing part (FIG. 4A) and the
transmission mechanism (FIG. 4B) of the cutting-off machine;
and
FIGS. 5A, 5B show the cutting-off machine in the front pivot
position of the safety guard (FIG. 5A) and the rear pivot position
of the safety guard (FIG. 5B).
DETAILED DESCRIPTION
FIGS. 1A, 1B show a handheld, hand-guided power tool 10 according
to the present invention, which is designed in the form of a
cutting-off machine. Cutting-off machine 10 includes a machining
tool designed as a cutting-off wheel 11, which is driven by a drive
unit 12 in a rotation direction 13 around a rotation axis 14. All
drive components for cutting-off wheel 11 are combined as drive
unit 12. In cutting-off machine 10 illustrated in FIG. 1B, a cover
15 was removed, so that at least some drive components of drive
unit 12 are visible. Cover 15 may have a single-part or multi-part
design and is fastened to cutting-off machine 10 by screws.
Drive unit 12 includes a drive motor 17 situated in a motor housing
16, a transmission mechanism situated in a supporting arm 18 and
designed as a belt drive 19, and an output shaft 20, on which
cutting-off wheel 11 is mounted. Additional transmission components
are connectable as needed between drive motor 17 and belt drive 19.
A centrifugal clutch may be situated between drive motor 17 and
belt drive 19, which ensures that cutting-off wheel 11 does not
rotate at low rotational speeds, such as when idling or when
starting cutting-off machine 10. The centrifugal clutch includes a
clutch bell, against which the centrifugal weights are pressed
outwardly during operation, due to the centrifugal force. Drive
motor 17 drives a drive shaft 21 around a drive axis 22. The clutch
bell of the centrifugal clutch is rotatably fixedly connected to a
drive disk 23, which is rotatably supported on drive shaft 21.
Combustion motors or electric motors are used as drive motors 17
for cutting-off machine 10. All drive motors for motor-operated
electric power tools are combined under the term "electric motor";
the electric power tools may be cable-bound with a direct
connection to the grid or wireless without a direct connection to
the grid. Cutting-off machines which include a combustion motor may
be used with different types of cutting-off wheels 11--diamond
cutting-off wheels and abrasive cutting-off wheels--the cutting-off
wheels including cutting-off bodies made of bound abrasive
materials and/or grinding tools having diamond and CBN abrasive
materials. Cutting-off machines which include an electric motor may
be used with different types of cutting-off wheels 11: diamond
cutting-off wheels and bound, reinforced cutting-off wheels of type
41 or 42.
Cutting-off wheel 11 is surrounded by a safety guard 24, which is
used to protect the operator against flying dust particles and also
reduces the risk of injury by the operator reaching into rotating
cutting-off wheel 11 during the operation of cutting-off machine
10. Safety guard 24 is fastened in a hub area of cutting-off wheel
11 and is made up of a covering area 25, which covers cutting-off
wheel 11 over a covering angle of approximately 200.degree., and a
machining area 26, which exposes cutting-off wheel 11 over a
machining angle of 160.degree. for machining a workpiece. Safety
guard 24 is designed to be pivotable and may be pivoted around a
pivot axis 27 (FIGS. 2A, 2B) into a desired pivot position. To set
the pivot position, a hand grip element 28 is fastened to safety
guard 24, which may be used to apply the necessary forces to pivot
safety guard 24 around pivot axis 27.
A first handle 31, which has an operating unit 32 and is designed
as a top handle, is provided for operating cutting-off machine 10.
A handle which is situated above motor housing 16 is referred to as
a top handle. Alternatively, the first handle may be designed as a
rear handle, which is situated on the side of motor housing 16
facing away from cutting-off wheel 11. In addition to first handle
31, a second handle 33, which is situated between cutting-off wheel
11 and first handle 31, is provided for guiding cutting-off machine
10. In the exemplary embodiment shown in FIGS. 1A, 1B, second
handle 33 is designed as a separate gripping tube, or it may be
alternatively designed as a single piece with motor housing 16 or
another housing part.
FIGS. 2A, 2B show an enlarged representation of safety guard 24 and
belt drive 19 of cutting-off machine 10 from FIGS. 1A, 1B. Belt
drive 19 is situated in a supporting arm housing 35, which includes
a stationary, supporting housing part 36 and cover 15. FIG. 2A
shows belt drive 19, including mounted cover 15, and FIG. 2B shows
belt drive 19 without cover 15.
The drive of cutting-off wheel 11 takes place via drive motor 17,
belt drive 19 and output shaft 20. Drive motor 17 may be designed
as a combustion motor or as an electric motor. Drive motor 17
drives drive shaft 21 and drive disk 23 around drive axis 22. A
transmission element 38 designed as a drive belt is guided via
drive disk 23 and an output disk 39 supported on output shaft 20.
Output shaft 20 is rotatable around an output axis 40, which
coincides with rotation axis 14 of cutting-off wheel 11. Drive disk
23, drive belt 38 and output disk 39 form belt drive 19.
Alternatively, transmission mechanism 19 may be designed, for
example, in the form of a chain drive, in which the transmission
element between drive disk 23 and output disk 39 is designed as a
chain. Cutting-off wheel 11 is situated on output shaft 20 with the
aid of a flange 41 and is rotatably fixedly connected to output
shaft 20. Flange 41 and cutting-off wheel 11 are mounted on output
shaft 20, and cutting-off wheel 11 is situated between two flange
halves of flange 41.
A workpiece is machined with the aid of cutting-off machine 10 in
the area of cutting-off wheel 11 situated in machining area 26 of
safety guard 24. Safety guard 24 includes a fastening flange 42 in
the hub area of cutting-off wheel 11, which, in the exemplary
embodiment, is designed as a single piece with a side wall 43 of
safety guard 24; alternatively, the fastening flange may also be
designed as a separate part and connected to safety guard 24.
Fastening flange 42 is mounted on a matching counter-contour 44 of
the stationary housing part 36 and is designed to be adjustable
with respect to counter-contour 44 of housing part 36.
For gas-powered cutting-off machines, the European standard EN ISO
19432:2012, the U.S. standard ANSI B175.4-2013 and corresponding
standards in other countries define a minimum flange diameter
d.sub.min for flange 41, depending on the type of cutting-off wheel
11 (diamond cutting-off wheel or abrasive cutting-off wheel) and on
wheel diameter D of cutting-off wheel 11 (D.ltoreq.250 mm, 250
mm<D.ltoreq.300 mm, 300 mm<D.ltoreq.350 mm and 350 mm<D).
For diamond cutting-off wheels, minimum flange diameter d.sub.min
is: d.sub.min37.5 mm for D.ltoreq.250 mm, d.sub.min=45 mm for 250
mm<D.ltoreq.300 mm, d.sub.min=52.5 mm for 300 mm<D.ltoreq.350
mm and d.sub.min=60 mm for 350 mm<D. For abrasive cutting-off
wheels, minimum flange diameter d.sub.min is: d.sub.min63.5 mm for
D.ltoreq.250 mm, d.sub.min=75 mm for 250 mm<D.ltoreq.300 mm,
d.sub.min=87.5 mm for 300 mm<D.ltoreq.350 mm and d.sub.min=100
mm for 350 mm<D.
Maximum cutting depth t.sub.max achievable by cutting-off wheel 11
in a workpiece is then achieved if flange diameter d.sub.f of
flange 41 corresponds to minimum flange diameter d.sub.min and no
components of cutting-off machine 10 additionally limit the cutting
depth. Maximum cutting depth t.sub.max is defined by half the
difference between wheel diameter D of cutting-off wheel 11 and
minimum flange diameter d.sub.min, of flange 41:
t.sub.max=1/2*(D-d.sub.mim). In gas-powered cutting-off machines 10
and a diamond cutting-off wheel, maximum cutting depth t.sub.max
is: t.sub.max=106.25 mm for D=250 mm, t.sub.max=127.5 mm for D=300
mm, t.sub.max=148.75 mm for D=350 mm and t.sub.max=170 mm for D=400
mm. In gas-powered cutting-off machines and an abrasive cutting-off
wheel, maximum cutting depth t.sub.max is: t.sub.max=93.25 mm for
D=250 mm, t.sub.max=112.5 mm for D=300 mm, t.sub.max=131.25 mm for
D=350 mm and t.sub.max=150 mm for D=400 mm.
FIGS. 3A, 3B show flange 41 and safety guard 24 in a front pivot
position (FIG. 3A) and a rear pivot position (FIG. 3B). Safety
guard 24 is designed to be pivotable around pivot axis 27 between
the front pivot position and the rear pivot position; in the
exemplary embodiment, the pivot range of safety guard 24 is limited
to an angle range of approximately 60.degree.. As in the exemplary
embodiment, safety guard 24 may be situated in any arbitrary pivot
position between the front and rear pivot positions; alternatively,
discrete pivot positions may be provided for safety guard 24
between the front and rear pivot positions.
Pivot axis 27 of safety guard 24 is different than output axis 40
of output shaft 20. Pivot axis 27 is displaced by a distance 4 with
respect to output axis 40 into covering area 25 of safety guard 24.
The full angle of cutting-off wheel 11 of 360.degree. is divided by
safety guard 24 into a covering angle and a machining angle.
Covering area 25 of safety guard 24 determines the covering angle,
and machining area 26 of safety guard 24 determines the machining
angle. In the exemplary embodiment, the covering angle is
approximately 200.degree., and the machining angle is approximately
160.degree..
Safety guard 24 has a first outer contour 45. The angle range, in
which first outer contour 45 of safety guard 24 has distances from
output axis 40 which are less than or equal to half of minimum
flange diameter d.sub.min, is defined as first angle range
.theta..sub.1. The maximum distance which first outer contour 45
has in first angle range .theta..sub.1 is defined as first maximum
distance b.sub.1. First maximum distance b.sub.1 corresponds to
half of minimum flange diameter d.sub.min. The position and size of
first angle range .theta..sub.1 change during the pivoting of
safety guard 24 around pivot axis 27. FIG. 3A shows first angle
range .theta..sub.1 in the front pivot position of safety guard 24,
and FIG. 3B shows first angle range .theta..sub.1 in the rear pivot
position of safety guard 24.
FIGS. 4A, 4B show supporting housing part 36 (FIG. 4A) and
transmission mechanism 19 (FIG. 4B) in the area of output shaft 20.
To be able to achieve maximum cutting depth t.sub.max with the aid
of cutting-off wheel 11, not only safety guard 24 but also
supporting housing part 36 and transmission mechanism 19 must be
designed in such a way that their outer contours do not project
over flange 41.
Supporting housing part 36 has a second outer contour 46. The angle
range, in which second outer contour 46 of supporting housing part
36 has distances from output axis 40 which are less than or equal
to half of minimum flange diameter d.sub.min, is defined as second
angle range .theta..sub.2. The maximum distance which second outer
contour 46 has in second angle range .theta..sub.2 is defined as
second maximum distance b.sub.2. Second maximum distance b.sub.2
corresponds to half of minimum flange diameter d.sub.min.
Transmission mechanism 19 includes output disk 39, which is
situated on output shaft 20, transmission element 38, which
transmits a movement of drive motor 17 to output disk 39, and cover
15, which covers output disk 39 and transmission element 38. Output
disk 39 and transmission element 38 are rotating components, which
must be covered with the aid of cover 15 to meet safety
requirements. The outer contour of transmission mechanism 19 is
therefore determined by cover 15. Transmission mechanism 19 has a
third outer contour 47. The angle range, in which third outer
contour 47 of transmission mechanism 19 has distances from output
axis 40 which are less than or equal to half of minimum flange
diameter d.sub.min, is defined as third angle range .theta..sub.3.
The maximum distance which third outer contour 47 has in third
angle range .theta..sub.3 is defined as third maximum distance
b.sub.3. Third maximum distance b.sub.3 corresponds to half of
minimum flange diameter d.sub.min.
If transmission mechanism 19 does not include any rotating
components, cover 15 may be eliminated or be provided with a
different design. The condition that the maximum distance of
transmission mechanism 19 from output axis 40 is less than or equal
to half the minimum flange diameter in third angle range
.theta..sub.3 must generally be met for each subcomponent of
transmission mechanism 19. These include output disk 39, which is
situated on output shaft 20, and transmission element 38, which is
situated on output disk 39. Output disk 39 has a fourth maximum
distance b.sub.4, transmission element 38 has a fifth maximum
distance b.sub.5, and cover 15 has a sixth maximum distance
b.sub.6. In the exemplary embodiment, sixth maximum distance
b.sub.6 of cover 15 corresponds to third maximum distance b.sub.3
of transmission mechanism 19, since third outer contour 47 of
transmission mechanism 19 is determined by cover 15.
FIGS. 5A, 5B show cutting-off machine 10 according to the present
invention, including safety guard 24, supporting housing part 36
and transmission mechanism 19 in the front pivot position of safety
guard 24 (FIG. 5A) and in the rear pivot position of safety guard
24 (FIG. 5B).
Safety guard 24 does not project over flange 41 in first angle
range .theta..sub.1, supporting housing part 36 does not project
over flange 41 in second angle range .theta..sub.2, and
transmission mechanism 19 does not project over flange 41 in third
angle range .theta..sub.3. The intersection between first angle
range .theta..sub.1, second angle range .theta..sub.2 and third
angle range .theta..sub.3 is defined as outcut angle .theta.. In
outcut angle .theta., safety guard 24, supporting housing part 36
and transmission mechanism 19 have distances from output axis 40
which are less than or equal to half of minimum flange diameter
d.sub.min. When the operating angle of cutting-off machine 10
according to the present invention is within outcut angle .theta.,
maximum cutting depth t.sub.max is achievable, which is defined as
half the difference between wheel diameter D of cutting-off wheel
11 and minimum flange diameter d.sub.min.
Since safety guard 24 is pivotable around pivot axis 27, the
position of first angle range .theta..sub.1 changes relative to
second angle range .theta..sub.2 of supporting housing part 36 and
third angle range .theta..sub.3 of transmission mechanism 19. FIG.
5A shows outcut angle .theta. in the front pivot position of safety
guard 24, and FIG. 5B shows outcut angle .theta. in the rear pivot
position of safety guard 24. In the exemplary embodiment, outcut
angle .theta. is approximately 62.degree. in the front pivot
position and approximately 55.degree. in the rear pivot position.
Outcut angle .theta. is different than zero in all pivot positions
of safety guard 24 between the front and rear pivot positions.
Since outcut angle .theta. is different than zero for all pivot
positions of safety guard 24, maximum cutting depth t.sub.max is
achievable in each pivot position of safety guard 24. Cutting-off
machine 10 must only be oriented by the operator in such a way that
the operating angle is within outcut angle .theta..
* * * * *